Help Center> Data Lake Insight> Spark SQL Syntax Reference> Built-In Functions> Aggregate Functions> covar_samp
Updated on 2023-10-25 GMT+08:00
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covar_samp

This function is used to return the sample covariance between two columns of numerical values.

Syntax

covar_samp(col1, col2)

Parameters

Table 1 Parameters

Parameter

Mandatory

Description

col1

Yes

Columns with a data type of numeric. If the values are of any other type, NULL is returned.

col2

Yes

Columns with a data type of numeric. If the values are of any other type, NULL is returned.

Return Values

The return value is of the DOUBLE type.

Example Code

  • Calculates the sample covariance between the inventory (items) and the price of all offerings. An example command is as follows:
    select covar_samp(items,price) from warehouse;

    The command output is as follows:

    _c0        
1.242355
  • When used with group by, it groups all offerings by warehouse (warehourseId) and returns the sample covariance between the inventory (items) and the price of offerings within each group. An example command is as follows:
    select warehourseId, covar_samp(items,price) from warehourse group by warehourseId;

    The command output is as follows:

    warehouseId _c1        
city1    1.03124   
city2    1.03344   
city3    1.33425
Parent topic: Aggregate Functions